Add UTF8 BOM as gulp pipe

gulp-addBOM.js

function addBOM() {
	// Creating a stream through which each file will pass
	return through.obj( function ( file, enc, cb ) {
		if ( file.isNull() ) {
			// return empty file
			cb( null, file );
		}
		var buf = file.contents;
		var decoder = new StringDecoder( 'utf8' );
		var contents = decoder.write( file.contents );
		var missingBOM = ( contents[0] !== 0xEF && contents[1] !== 0xBE && contents[2] !== 0xBB );
		if ( file.isBuffer() ) {
			if ( missingBOM ) {
				file.contents = new Buffer( '\ufeff' + contents, 'utf-8' );
			} else {
				file.contents = new Buffer( contents, 'utf-8' );
			}
		}
		if ( file.isStream() ) {
			var stream = through();
			if ( missingBOM ) {
				stream.write( '\ufeff' + contents, 'utf-8' );
			} else {
				stream.write( contents, 'utf-8' );
			}
			file.contents = stream;
		}
		cb( null, file );
	} );
}